NCIS, FBI and MI6 continue an international manhunt for an escaped British spy who is targeting current and former agents.

The NCIS team investigates the murder of a Marine Sergeant in the States who was hailed as a war hero for his efforts overseas. Also, Gibbs turns to Doctor Grace Confalone for advice after he uncharacteristically unravels and abandons his team at a crime scene investigation.

NCIS investigates Marine Corporal Laney Alimonte after evidence suggests she murdered her neighbor while being treated for insomnia by a hypnotherapist. Also, Gibbs befriends his new neighbors after the 9-year-old’s baseball crashes through his window.

NCIS uncovers a secret dogfighting ring, which leads to an unexpected move by one of the team members.

NCIS investigates the apparent suicide of a retired Navy officer who was in Palmer and Knight's grief group; Torres gets a call from NCIS Special Agent Jane Tennant to come to Hawai'i.

The crossover continues on NCIS: Hawai'i S01E18 T'N'T (II).

When an infamous arms dealer, Reymundo Diaz, is released from prison and bodies start piling up, Torres is forced to face the repercussions of his actions during an undercover operation he worked on years ago.

When a dead body is found at an ancient burial site that is thought to be cursed, the team tries to determine the motive and the symbolism behind the crime. Also, as Torres continues therapy with Dr. Grace, he discovers that their lives are in danger.